I tried a few more things.
“particle list” shows that the device is online and has the digitalread/write analogread/write functions
“particle call device_name digitalwrite D7, HIGH” turns the LED on and it stays on which confirms the Blink program is not running. (and probably not actually installed)
I then compiled the program: “particle compile photon xxx.ino”
and “particle flash device_name photon_firmware_yyyyy.bin”
Flash success.
Web IDE events shows correct events and program seems to runs correctly (ie: variables and functions and JavaScript API calls are working) but I need to reinstall device in panel to confirm but it looks good.
I then tried to flash with the web IDE but that still doesn’t work. (“flash unsuccessful - Device not discoverable or is offline”)
The program that was flashed via USB still behaves correctly so the unsuccessful flash via the web IDE did not affect the device (which confirms that the “successful” flash of Blink didn’t actually work.)
I can now flash this device with the CLI but not with the web IDE. My other device can be flashed via the web IDE (same program, same software rev on both devices (rev 1.4.4) so the problem appears to be something to do with the particular device.
Steve